Some articles of drug medicines or specimens handled in medical institutions such as hospitals and of foods handled in supermarkets need during their transportation to keep cold or warm within a predetermined temperature range in order to maintain their quality. As a conventional method of keeping cold or warm with the articles such as drug medicines, specimens or foods, there is a method of housing the articles in a heat-insulation transport container, in which a solidified or molten heat storage materials are accommodated beforehand to use this melting latent heat. In order to maintain for a long time the temperature of articles to be kept cold or warm (hereinafter called as “temperature-regulation required articles”) within a predetermined temperature rage (hereinafter called as “regulated temperature range”), it is necessary to utilize a heat storage material or heat storage materials having a melting temperature in a predetermined temperature range and a large melting latent heat.
The conventional cheap and safe heat storage material generally used and with a large melting latent heat is composed mainly of water. As is known, the melting temperature of water is in general around 0° C. If it is necessary to manage the temperature of the articles at the regulated temperature range of 0° C. or less, a freezing point depressant may be added to the water to adjust the melting temperature thereof below 0° C. However, in case that it is necessary to manage the temperature of the articles at the regulated temperature range of more than 0° C., such heat storage material composed mainly of water cannot be used. Concrete examples of the regulated temperature range of the articles over 0° C. are as follows. The appropriate regulated temperature range in transportation of blood and blood plasma is substantially about 4-6° C., the appropriate regulated temperature range in transportation of drugs is substantially abut 2-8° C., and the appropriate regulated temperature range in transportation of blood platelet and biological organization is substantially about 18-22° C.
Heat storage material compositions suitable for the regulated temperature range of more than 0° C. have been developed for a long time and really used. For example, in patent document 1, disclosed is an apparatus for thermally packaging an item or temperature-regulation required article. The apparatus includes at least one container substantially filled with phase change (transition) alcohol. The alcohol used in the apparatus of this patent document 1 is an alcohol of C6-C20, particularly a higher alcohol such as 1-decanol or 1-dodecanol. Namely, this patent document 1 discloses technique for keeping the temperature in the heat storage material vessel constant by utilizing transition of phase of the alcohol so as to substantially prevent temperature change in the apparatus.
Patent document 2 discloses a heat storage material composition consisting of (a) sodium sulfate decahydrate: 60-85 parts by weight (pts·wt.) and (b) inorganic salt such as ammonium chloride: 15-40 pts·wt., and containing cross-linked carboxymethylcellulose of 0.1-10 pts·wt. per 100 pts·wt. of heat storage component having melting temperature of 5-15° C. Namely, this patent document 2 discloses a heat storage material composition suitable for cooling air conditioning, by utilizing the sodium sulfate decahydrate with a high latent heat capacity, so as to have property of little falls in latent heat capacity even if it is repeatedly used for a long period of time and also property of small difference between the solidification temperature and the melting temperature.
On the other hand, patent document 3 discloses a heat storage material composition used for maintaining temperature principally higher than the normal temperature. This heat storage material composition is composed of at least one selected from a group consisting of a higher fatty acid having carbon number of 10 or more and a higher alcohol having carbon number of 10 or more, and a hydrous water absorptivity polymer. Namely, this patent document 3 discloses a heat storage material in solid state to be hard to catch fire, having a relatively high melting temperature and a high latent heat capacity by impregnating the above-mentioned higher fatty acid and/or higher alcohol in a hydrous held water absorptive polymer.